Do I have any legal
property rights to allow or disallow a guest to enter my house?

Here's a situation: I am married to my spouse. We don't have any intention of getting a divorce. My spouse wants to invite a guest to stay with us in our jointly owned house indefinitely (hopefully only for a few months). I unequivocally don't want this guest. Is there nothing I can do to legally stop this guest from staying, only because my spouse allows it? Can I do something physical like bar them from entering? Do my rights change if the guest was a family member of my spouse vs a total stranger?

If the answer is that I don't have any rights at all, does this mean that I can invite anybody I want to stay in a joint tenancy / ownership house for as long as I want without considering or even consulting the other
joint tenants / owner? This question is partly hypothetical, but highly relevant to someone I know.

Hi Arlen, since you and your spouse's rights to the home as joint tenants is equal, you have as much right to exclude someone from your house as he does to invite someone to stay. That being the case, no you have no legal rights to exclude his guests. There is no overriding law that gives either of you superior rights in this matter, it is a domestic dispute and it is up to you to sort it out. The law will not intervene unless there is some other legal issue such as restraining orders relating to one or more of the parties etc.

I was wondering about this situation and imagine that it happens on a fairly regular basis around Australia.

I agree the owners have competing rights however I was thinking that legal public policy considerations would tend towards keeping the peace and therefore encourage the separation of the disputing parties (owner versus third-party).

I was unable to find any cases supporting either owner's rights.

I'm not a lawyer, just someone with life experience and a little bit of legal knowledge. Not enough knowledge to be certain, but enough to be useful in some situations, and dangerous in others